Generating authentication codes

1. A method for use in generating an authentication code associated with an entity, the method comprising:

retrieving a stored secret associated with an entity;

at a first point in time after a first time interval, determining a first dynamic value associated with the first time interval;

determining a first authentication code based on the first dynamic value;

at a second point in time, determining a second dynamic value associated with a second time interval, wherein the first and second dynamic values are based on a clock;

determining a second authentication code based on the second dynamic value, wherein determining the second authentication code is triggered by an event occurring prior to the end of the first time interval, wherein the amount of time between the first and second points in time is less than the length of the first time interval, wherein the event is initiated by a user; and

wherein the first and second authentication codes are derived by an entity authentication device from the stored secret.

2. The method of claim 1 further comprising:

altering a clock;

wherein the second dynamic value is based on the clock.

3. The method of claim 1 further comprising:

altering a clock output;

wherein the second dynamic value is based on the clock output.

4. The method of claim 1 further comprising:

advancing a clock;

wherein the second dynamic value is based on the clock.

5. The method of claim 1 further comprising:

advancing a clock output;

wherein the second dynamic value is based on the clock output.

6. The method of claim 1 wherein the first and second time intervals are the same length.

7. The method of claim 1 wherein at least one of the determinations of the first and second authentication codes avoids use of the stored secret.

8. The method of claim 1 wherein at least one of the first and second authentication codes is retrieved from a data structure that comprises a plurality of authentication codes.

9. The method of claim 1 wherein at least one of the determinations of the first and second authentication codes is further based on the stored secret.

10. The method of claim 1 , wherein the event is caused by the entity.

11. The method of claim 1 , wherein the event is a button press.

12. The method of claim 1 further comprising:

updating a display based on at least one of the first and second authentication codes.

13. A system for use in generating an authentication code associated with an entity, the system comprising:

first logic retrieving a stored secret associated with an entity;

second logic, at a first point in time after a first time interval, determining a first dynamic value associated with the first time interval;

third logic determining a first authentication code based on the first dynamic value;

fourth logic, at a second point in time, determining a second dynamic value associated with a second time interval, wherein the first and second dynamic values are based on a clock;

fifth logic determining a second authentication code based on the second dynamic value, wherein determining the second authentication code is triggered by an event occurring prior to the end of the first time interval, wherein the amount of time between the first and second points in time is less than the length of the first time interval, wherein the event is initiated by a user; and

wherein the first and second authentication codes are derived by an entity authentication device from the stored secret.